Railway-traffic-controlling apparatus



Oct; 4-,;1927. 4,644,428

L. O. GRONDAHL RAILWAY TRAFFIC CONTROLLING APPARATUS Original Filed Au jsL 1925 IN ENTORZ ca K m MATTORN/EY Patented Get. 4, 1927.

aura tries rarest LABS 0. snowmen, or rrr'rsnonen, rnnrisvnvenre, ASSIGNOR TO THE U ION swIreH & srenar. COMPANY, or swrssvens,

rnnnsvnvnnre.

RAILWAY-rearsrc-coivrnotnrne arrnaatrns.

Application filed' llu g ust 31, 1928, Seria1 No. 680,352. Renewed March 2, 1927..

My invention relates to railway trafiic controlling apparatus. V p

I will describe one form of apparatus embodying my invention, and will then point 5 out the novel teaturesthereof in claims.

In the accompanying drawings, F lg. 1 is a diagrammatic view showing one form of apparatus embodying my invention, and Fig.

2 is an end v ie-w'oi one of the translating devices D shown in Fig. 1.

Referring first to Fig. 1, the "reference character Q designates the track rails of a railway along which trafiic normally moves in the direction indicated by the arrow. lhese rails are divided by insulated joints 22 into a plurality of blocks Ay-B, BC, etc. Located adjacent the entrance end of each block is a "signal designated by the reference"character S' with an exponent correspondingto the location, each of which signals in the iiorm here shown comprises three electric lamps'G, Y and R, adapted when lighted to indicate .proceed, caution and stop, respectively. These signals are controlled by the means which I'will now describe.

lleiterring particularlyto the apparatus lo- 2)','the outer surfaces of which plates are coated with thermo-sensitivesubstances and2 respectively. Each thermo-sensiive substance is in turn surrounded by a elm-cylind ical electrode 3 or 3 of metal. -..ocated within the tube formed by these elements is an electron emitting member 19, vhiclr, "as here shown, is a filament adapted to be heated by the passage of an electric current, and interposed between the filament V and the two plates is a grid 11, which, as will be explained hereinafter, serves to control the flow of electrons from the filament 19 to the plates 4 and'd 1 The device E issirnilar in every respect to the device D. The device Fis also similar to device D, except that it contains no grid. The device F is provided, however, with a w nding 13 adapted when supplied with electriccurrent to create a magnetic field which prevents the flow of electrons from the filament 21 to' the plateslO and 10.

Each device, D, E and Ewillusually be -.enclosed in'a bulb or tube from which the air is exhausted or which contains a suitable non-oxidizing gas.

device D, E and F is'so designed that Each the thermo-sensltive substances are heated PENNSYLVANIA, A CORPORATION OF any event, the bombardment of the plates is cue to; the emission of electrons'from thev filament." Thesethermosensitive substances that the electrical resistance of each subnave negative temperature coefficients, so

stance decreases with an increase of thetem- 7 pc-rature of the substance. These substances may, for e: an.iple, be cupric oxide, cuprous' exit e, or any other substance having high negrative temperature coefficients.

electric current which is supplied by" the secondary 23 of a transformer T these filaments being connected between points "27 and 28 on saidsecondary. The filament circuits will be obvious from the drawing with; out further explanation.

constantly supplied with alternating current from a transmission line 25, which in turn'is supplied with current by a generator26fi The device is providedwith a plate circuit which passes from point 27' on secondary r I i '80 The primary 2 1 of the transit'ormerT is 23, through wire 51, filament 19, plates 4 and 4 in multiple, wires .35 and 35? .in multiple, wire 33, and wire 34 to point 32 on secondary 23. The device E is provided with a similar plate circuit which passes from point 27 on secondary 23, through wire 51, filament 20, plates 7 and 7 in. multiple, and wires 36 and iA to point '32on secondary 23. The device F is provided with oneplate .rcuit which passes from point 27 onsecorid my 23, through wire 51, filament 21, plate 10, and wire 37 to point 29 on secondary 23. This device is provided with a second plate circuitwhich passes from point'27,

through wire 51, filament 21, plate 10*, and

wires 38,36 and 3&- to point 32'onflthe secondary of transformer T It will be observed, therefore, that the plate circuits of all the devices are constantly e'nergizedwith alternating current.

The winding'13 on device F is connected across the track rails of block A'B, which I rails,as will hereinafter appear, are suppliedwith alternating current of normal or reverse relative polarity. It follows that as long as sectionA B is unoccupied winding 13 is energized, with the result that bombardment against the plates 10 and 10 is prevented, and the thermo-sensitive substances 8 and 8f are consequently cool. VVhen block A--B is occupied, however, the winding 13' is'de-energized and there is then no opposition to the bombardment against the plates 10 and 10 with the result that the thermo= 'sensitive substances 8 and 8 are heated.

Connected in multiple with thewinding 13Iis the primary 15 of a transformer 1 1. The vmid'dlexpoint of secondary .52 of this transformer'is connected-by a wire 18 with i I vwire 53, and so with the filaments 19 and 20 :of the devices D and E, The right-hand terminalpf thesecondary 52 is connected by a .wire 17 with-the'grid 12 of the device E,

l while the left-hand terminal of, this second r-ary is. connected bya wire 16 with the grid 1 1 ofthe device D. It follows .that when the blOCli'A'fB. is unoccupied there will be a difference of potential between the filament and grid of each. device D and E, but that at I any given instant the polarity of the grid in the device D will be opposite to the polarity :of the grid in device E. D :Each vdevice D- and E is so designed and proportioned that if the plates are positive with respect to the filament at the same instant that the grid is positive with respect to the filament, afree flow of electrons will oc- I cur-from filament to plates, so that the thermo-sensitive substances in these devices will be heated lfyhowev-er, the grid is'deenergizedgor if the plate is positive with respect 7 to'the' filament at the same instant that the Y grid.v is negative with respect'to' the filament, r the flow of electrons from filament to plates will be preventedand so the thermo-sensitive l r substances will becool.

I The control of signal S isas follows:

: The proceed lamp G is provided with a 1. circuit-which passes from point 30 on trans-- former secondary 23, through wire 39, lamp 'G, wire 40,'thermo-sensitive substance 2 of 3am transformer secondary 23.

tion lamp Y is provided with a circuit which device D,-a nd wires 35", 33' and 3 f to point The can- ]5asses from point30, through wires 39 and "41,'lamp Y, wire 4:2,,thermo-sensitive substance 5 of device andwires' 36 and 34 to point 32. The stop lamp R is provided with-acircuit which passes-from point 30,

throughwires 39,41 and 43, lamp R, wire 44, thermo sensitive substance 8 of device F and wires 38, 36 and 34 to point 32. Each of these circuits is ,so designed and propor- ",tioned'thatthe lamp is extinguished when the thermo-sensitive substance is cool but is lighted when the thermo-sensitive substance I is heatedby bombardment.

Inladdition to the control of the lamps of signal S the three devices D, E and F also control the supply of current to the rails vof block BC. When winding 13 on device F is de-energiZ-ed so that the thermosensit-iv-e substances of this device are heated, current passes from point 29 on transformer secondary 23, through wire 37, .thermo-sensitive substance 8', wires 47 and 46, the lower track rail Q, then through the apparatus at point C to the upper track rail Q, and from thatrail throughwire 4-5 topoint 31 on transformer secondary 23. This current I will term current of reverse relative polarity. When winding 13 and transformer primary 15 are energized with current of normal relative polarity, the thermo-sensitive substances in device D are heated, and

current then flowsv from point 32 on transformer secondary 23, through wires 34, 33 and 35, thermo-sensitivesubstance 2 of device D, wires 50, 4:8 and 46 to the ,lowerrail Q, thence through the apparatus at point C and the upper rail Q, and from that rail through wire 45"to point- 31 on transformer secondary. 23. If the current supplied to transformer primary 15 is of reverse relative polarity, the thermo-sensitive substances in device E are heated, whereas the thermo-seir sitive substances in device are cool, so that current then passes from point 32, throughwires 34 and 36, thermo-sensitive substance 5 of device E, wires 4:9, 48and 16 lower rail and wire 45 to point 31 on secondary 23.

Q, the apparatus at point-C, upper rail Q When either device D or E is functioning in I this manner, current of what I will term normal relative polarity is supplied to the railsof block B C, it being understood thatat such times device'F is not functionin and so the supply of current of reverse relative polarity is discontinued.

an I I The grid and plate circuits for devices D and E are so arranged that when current of normal relative polarity is supplied to the rails of block AB the plates of device D are positive with respect to the filament at the same instant that the grid oftliis device is positive with respect to the filament so that this device D is active. Proceed lamp G is then lighted and current-of normal relative polarity is supplied to the rails of block- B-C. At such'timc the plates of device E are positive with respect to the filament at; the same instant that the grid of this device so that the cautior lamp Yisthenliglatd 3 The device F i and current of normal relative polarity is again supplied to the rails of block 13-43. Device D is then inactive because its plates are positive with respect mum filament at the same instant that its grid ii's negative w'th respect to the filament, so that lamp G is extinguished. When device E is active,

. device F is, of course. inactive, because its winding 13 is energized, it being understood that the relative polarity of the current supplied to winding 13'is immaterial in so far as concerns the suppressing of the flow OI electrons from filament to plates in this device. When block A-B is occupied, devices D and E are both inactive because'of the grids of these devices are de-energized, so that lamps. G and Y are both extinguished. Device F is then active, howevenbecau'se its Winding 13 is tie-energized, so that stop lamp R-is lighted and current-of reverse relative polarity is supplied to the rails of block Theapparatus located at'each point Av and-C is exactly the same as the apparatus located at point Band described in detail hereinbefore. p v I As shown in the drawing, the block immediately to the left of point A is occupied by a train W, so that the device F at point is active and the devices D and E at this point are inactive; Stop lamp R of signal proceed lamp G of signal S is lighted and current of normal relative polarity is supplied to the rails of the block to the right of point C.

I do not claim as my invention the broad combination of a thermo-sensitive substance heated by bombardment of electrons from a hot filament and a circuit controlled by the temperature of said substance, such invention beingfdisclosed and claimed in an application for Letters Patent of the United States filed by Frank N. VVatermanon the 19th day of Gctober, 1923, Serial No. 669,578. a I v i Although I have herein shown and described only one form of apparatus embody ing my invention, iti-s understood that various changes and modifications may be made therein within. the scope of the appended claims without departing from the spirit and scopeot my invention.

Having thus described my invention, vwhat I claim is:

t 1. Railway traflic controlling apparatus said member, train' controlled means for governing the bombardment of said substance, and a traflic governing device con-- trolled by the temperature of said substance.

2. Railway traflic controlling apparatus comprising an electron emitting member,ya thermo-sensitive substance heated by bom' bardment due to emission of electron-s from said member, train controlled means for governing the bombardment of said substance, a circuit including said substance and a source of current, and atraflic governmg device controlled by the flow of current 7 1nsaid circuit.

3. Railway traflic controlling apparatus comprising an electron emitting'member, a thermo-sensitive. substance heated-by bombardment due to emission of electrons from said member, train controlled means for governing device. w. I, p

4. Railway t-rafliccontrolling apparatus comprising an electron emitting member, a thermo-sensitive substance heated by .bombardment due to emission of electrons-from said member, a track circuitincluding a source of current and the'rails of a railway track, means controlled by said track circuit for governing" the bombardment of said 'substance, and a trafiic governing device controlled by the temperature of said substance. 5. Railway traflic controlling apparatus comprising an electron emitting member, a

thermo-sensitiv-e' substance heated by bombardment due to emission of electrons from said member, a track circuit includinga source of'current and the rails of a railway track, means controlled by said track circuit for governingthe' bombardment of saidsubstance, a circuit including, said" substance and. a source of current, and atraflic. gov erning device controlled by the flow: of current in said circuit. 7 i I :6. Railway trafiic controlling apparatus comprising an electron emitting member, a thermo-sensitive substance heated by bombardment due to emission of electrons from said member, a Winding arranged when energized to create a magnetic field which prevents such bombardment of said substance, a track circuit includinga source of current and the rails of arailway track and said winding,and a traflic governing device controlled by the temperature of saidfsubstance. 7

7. Railway tr'aflic.

controlling apparatus comprising anelectron emitting member, a

thermo-sensitive substance heated by b'ombardmentdue to emission of electrons from said member, a windingarran'ged when ,en-,

ergizedto create a magnetic field which prevents such, bombardment of said substance,'a

:track circuit including a source of current stop lamp.

- bardment dueto emission of electrons from v and the rails of a railway track" and said winding, and a signal circuit 'lIlCllld111gS211d substance and a source or current and a q8..jRailway trafiic controlling apparatus comprising an electron emittingmember, a thermo-sensitive substance heated by' bombardment due to emission of electrons from said member, a winding arranged when energized to cr'eate a magnetic field which prevents such bombardment'of said substance, train controlled means for gove'rn-.

ing the energization of said winding, and a tr'aflic governing device controlled by r the temperature ofsaid substance.

9; Railway traflicycontrolling apparatus comprising an electron emitting member, a thermossensitive substance heated by bomsaid "member, 1 a grid'nfor controlling the bombardmentofsaid substance, train con- .trolled means ion-governing the energlzation of said grid, and traffic governing "means controlled bythe temperature of said substance;

traffic controlling apparatus =,comprising an electron emitting member, a plate, athermo-sens1tive substance .ran'ged to be heated by bombardmentdue a to electrons flowing from said member to said plate, a plate circuit including said -memb'er' and said plate and a source of alternating current, a grid interposed'between said memberiand said plate, a' grid circuit including: said member and 'saidgrid, the parts beingso arrangedthat said thermosensitive substance'is heated by bombardment when said grid circuit is energized by alternating :current in aphasewvitli said i 1 "plate circuit current 'but'not when the grid.

circuit is energized by alternating. current of the opposite phase and 'when the grid circuit is de-energized, train controlled means for governing the energization'ot' said grid fcircuit, and tratlic governing means controlledEby the temperatur'e of said thermosensitivesubstance; 1 w v I 11. Railway traificcontrolling apparatus comprising an electron emitting member, a plate, a, thermo-sensitive. substance arranged to be heated by bombardment due to electrons flowing from said member-to said plate,a' plate circuit including said memher and said plate and a source ofalternatmember and 's'aid 'plate, a grid circuit including said member and said grid, the parts being so arranged that said thermo-sensitive substanceis heated by bombardment -when said-grid circuit isenergized by alternating current'in phasewith said plate circuit but not when salidfgrid circuit is energized by al+ mg current, a grid interposedbet-ween said.

'ternatingcurrent of the opposite phase and when the grid circuit is de-energized, train controlled means forgoverning the energi- 'zation ofsaid'grid circuit, a circuit including said 'thermo-s ensitive substance and a source of current, and a traffic governing device controlled by the flow ofcurrent in said last mentioned circuit.

a 12. Railway-traffic controlling apparatus comprislng an electron emlttmg member, a'

gized by alternating current of the opposite phase and when the grid circuit is deenergized, a track circuit including a source of. current and the rails of a railway track,

means controlled by said track circuit for governing the energization of said grid circuit, and traffic governing means controlled by'the temperature of said thermo sensitive substance. V I r 13. Railway traitic controlling apparatus comprising an electron emitting member, a plate, a tliermo-sensitive substance arranged to be heated by bombardment due to electrons flowing from said member to said plate, a plate circuit including said, member and said plate and a source of alternating current, a grid interposed between said member andsa-id plate, av grid circuit including said member and said grid, the parts being so arranged that said thermo-sensitive substanceis heated by bombardment when saidgrid, circuit is energized-by"alternating cur-' rent in phase with said plate circuit current but not When the grid circuit is energized by alternating current or the opposite phase and when the'grid circuit is de-energized, a track circuit including track rails and a source of alternating current reversibly connected therewith and the primary of a transformer, the secondary of said Ltransformer being connected withsaid grid'circuit, and trafiic governing means controlled by the tempera ture of said thermosensitive substance.

14. Railway 'trafii'c controlling apparatus comprising an electron emitting member, a

plate, a thermosensitive substance arranged to be heated by bombardment dueto electrons flowing from said member ,to' said plate, aplatecircuit including said member and said plate and a source of alternating current, a grid interposed between said member and said plate, a grid circuit 111-" circuit, a circuit including said thermo-sen current in phase with said plate circuit current but not when the grid circuit is ener gized by alternating current of the opposite phase and when the grid circuit is de-energized, a track circuit including track rails and a sourceof alternating current reversibly connected therewith and the primary of a transformer, the secondary or said transformer being connected with said grid sitive substance and asource of current, and a traffic governing device controlled by the flow of current in said last mentioned circuit. r

comprising an 'electron'emitting member,- a

7 plate, a thermo-sensitive substance arranged to be heated by bombardment due to elec trons flowing from said member to said plate, a plate circuit including said member and said plate and a sourceof alternating current, a grid interposed between said member and said plate, a grid circuit including said member and said grid, the parts being so arranged that said thermo-sensitive substance is heated by bombardment when said grid circuit is energized by alternating current in phase with said plate circuit, current but not when the grid circuit is energized by alternating current of'the opposite phase and whenthe grid circuit is'deenergized, a track circuit including track rails for at times energizing said grid circuit with alternating current in phase with the plate circuit current and at other times energizing the grid circuit with alternating current opposite in phase to the current in the plate circuit, and traffic governing 'means controlled by the temperature of said thermosensitive substance.

16. Railway traffice controlling apparatus comprising two devices, each device including an electron emitting member,,a plate, a grid interposed between the member and the plate, and a thermo-sensitive substance arranged to be heated by bombardment due.

to electrons flowing from the member to the plate; a plate circuit for each device including the plate and member of such device and a source of alternating current, a grid circuit for each device including the member spect to its member at the same instant that the grid of such device positive withrespect toits member While in the second arranged to be heated by bombardment due spect to its iilelilbef while in the second d'edevices are reversed, and trafiic governing means controlled by the temperature otsaid thermo-sensitive substances; 1 j

17. Railway trafiic controlling apparatus comprising two devices, each device including an electron emitting member, a plate, a grid interposed between the member and-- the plate, and a thermo-sensitive substance to electrons flowing from the member .to f

the plate; a plate circuit for each device p including the plate and member oi'such- 15. Railway trafiic controlling apparatus device and a source of alternating current, a grid circuit "for each device including the controlled means for supplying alternating current of one relative polarity or the other to said grid circuits, the apparatus being so arranged that when current of one relative polarityis supplied to said grid circuits the plate of the first device is positive with-rethe'grid cf such device ispositive withlre vice the plate is positive'with respect to the member at the same instant that thegrid is negative ,with respect to the member;

'men'ib'er and the grid of such device, train spect to its member at the same instant that,

whereas when current of the other relative polarity is supplied to said-grid circuits the elative instantaneous polarities in the two devices are reversed, a proceed signal controlled by the temperature 01 .the thermosensitive substance in one of said devices,- and acaution signal controlled by the tein-" perature of the thermo-sensitive substance in the other device;

18. Railway tra'tlic controlling 'apparatus comprising two devices, eachidevice including an electron emittingrmember, a plate,'a grid interposed between the member and the plate, and a thermo-sensitive substance arranged to be heated by bombardment due to electrons flowing from the member to the plate; a plate circuit for each device including the plate and member of such device and a source of alternating current, a transformer having the middle point of itssec ondary connected with the members of'said two devices and its two terminals connected with the two grids respectively,a track cir cuit including the track rails of a railway and a source of alternating current revers-: ibly connected therewith and the primary of said transformer, and trafiic governing means controlled by the temperature ofsaid thermo-sensitive substances.

19. Railway traffic controlling apparatus comprising three devices each including an flowing from the member to the plate, the

thermo-sensitive substance arranged to be heated .by bombardment due to electrons first and-secondidevice also including a grid Tinterposed between the member and the plate;a plate circuitfor each devlce 1nclud.

' ingthe plate and member of such device and "BLSOIIICG of alternating current, a winding for the third device arranged when energized to create a magnetic field which prevents bombardment on the plate of such device,two grid circuits for the first and sec ond devices, respectively; train controlled means'for at times supplying alternating current of one relative polarity to said grid "circuits and to said winding, and i'or at other times supplying alternating currentof the other relativepolarity to said grid cirwits and to said.winding,;and. for at still V the apparatus being so arranged t-hatvwhenother times discontinuing the supply of current to said grid circuits and said winding;

alternating current of onerelative polarity posite polarity, whereas when alternating I r current of the other relative polarity is sup-- grid of the first device aresimultaneously of i opposite polarity and the'plate and grid of l is supplied to said grid circuits'the plate and Fgridof the first device are simultaneously of the same polarity and the platesand grid of the second device are simultaneously or op plied to said grid circuits the plate and Ythewother device are vsimultaneously of the v same polarity, and traffic governing means controlled by the temperature of said thermo-sensitive substances. I

v '20. Railway trafiic controlling apparatusv 1 comprising three devices each including an electron emitting member, a plate, and a thermo-s'ensitive substance arranged to be heated by bombardment due; to electrons flowing from the member to the plate, the

V firstand seconddevice also including a grid interposed between the member and the plate; a plate circuit for each device in cluding the plate and Zmember of such device and a source of alternating current, a winding for the third device arranged when energized to'create a' magnetic field which prevents bombardment on the plate of such N device, two grid circuits for the first and second devices, respectively; train controlled means for at times supplying alternating current of one relative, polarity to said grid .timessupplying alternating currentof the circuits and to said winding, and for at other other relative polarity to said grid circuits and to said winding, and for at still other times-discontinuing the supply of current to saidgrid circuits and said winding; the

apparatus being so arranged that when alternating current of one relative polarity is supplied to said grid circuits the plate and grid of the first deviceare simultaneously of Tthe same polarity and the plate and grid'of i the second devicearesimultaneously of op posite polarity, whereas whenv alternating.

current of the other relative polarity is supplied to said grid circuits the plate and grid of thefirst device are simultaneously of op-' posite polarity and the plate and grid of the other device are simultaneously of the same 7 polarity, a hght slgnal comprising proceed,

caution and stop lamps, and circuits for said 7 lamps including the thermo-sensitive substances of said first, second andv third devices, respectively.

v 21. In combination, railway track divided into a pluralityof successive blocks; three devices for each block each device ineluding an electron emitting member, a plate,

and a thermo-sensitive substance arrangedto be heated by bombardment due to electrons :flowing from the member to the plate, the first and second device for eachblock also including a grid interposed between other member and the, plate, and the third device also including a winding arranged when energized to create a magnetic field which prevents bombardment on the plate of such device, a plate circuit for each device including the plate and member of, such device and a source of alternating current, means controlled by the devices for each block and operating to supply alternating current of normal relative polarity to the for supplying alternating current from the track rails to the winding for the-third device and also to the grid and member of the first and second devices, the apparatus being so arranged that when the polarity of the track current is normal the plate and grid of the first device are sin'lultaneously of the same polarity and the plate and grid of the I second device are simultaneously of opposite j polarities whereas when the polarity of the track current is reversed the plate and grid of the first device aresimultaneously of opposite polarities and the plate and gr-id of the second device are simultaneously of the same polarity; U

22. In combination, a railway track divided into a plurality "of successive blocks;

three devices for each block each device ineluding an electron emitting member, a,

plate, and athermo-sensitive substance ar-v ranged to be heated by bombardment due to electrons flowing from the member to the plate, the first and second device for each block'also including a grid interposed between the member and the plate, and the third device also lncludmg a winding arranged when energized to'create a magnetic 'field which prevents bombardment on the in the rear when the thermo-sensitive substance of the third device is heated, means for each block for supplying alternating cur rent from the track rails to the winding for the third device and also'to the grid and member of the first and second devices, the apparatus being so arranged that when the polarity of the track current is normal the plate and grid of the first device are smoultaneously of the same polarity and the plate and grid of the second device are simultane ously of opposite polarities whereas when the polarity of the track current is reversed the plate and grid of the first devlce-are,

simultaneously of opposite polarities and the plate and grid of the second device are simultaneously of the same polarity, and signals for the blocks controlled by the temperature of the thermo sensitive substance of said devices.

23. In combination, a railway track divided into blocks, devices for, each block including a thermo-sensitive substance and means for heating said substance by bombardment, train controlled means for each block for governing the bombardment in the associated devices, and means controlled by the devices of each block for supplying current to the rails of the block next in the rear.

24. In combination, a railway track divided into blocks, devices for each block including a thermo-sensitive substance and means for heating said substance by bombardment, train controlled means for each block for governing the bombardment in the associated devices, and means controlled by the devices of each'block for supplying cur rent of one polarity or. the other to the rails of the block next in the rear.

25. Railway traific' controlling apparatus comprising a thermo-sensitive' substance,

means for heating said substance'by electronic bombardment, and train controlled means for governing such bombardment.

26. Railway tratlic controlling apparatus comprising an electron emitting member, a

thermo-sensitive substance heated by bombardment due to emission of electrons from said member, and train controlled means for governing such bombardment. 27. The method of controlling .railway traflic which consists in heating athermosensitive substance by bombardment due to the emission or" electrons, and governing such bombardment by the presence and absence of trains.

28. Railway traffie controlling apparatus comprising an electron emitting member, a thermo-sensit-ive substance heated by'bombardment due to emission of electrons from said member, train controlled means for governing such bombardment, and a trafiic controlling device controlled by the temperature of said substance. 29. In combination, a section of railway track, a track circuit including the rails of said section and a source of current, an electron emitting member, a thermo-sensitive substance heated by bombardment due to Winding associated with said track circuit for governing such bombardment, and tratfic governing means controlled by said thermo- LABS o. G ON AHL.

emission of electrons from said member, a 

